I tried a mini SIP with a yogurt container, didn't work that well...
Went back to yogurt container with a half dozen holes in the bottom. No standing water.
Takes between 14 - 21 days before the leaves reach the edge of the container And roots are visible at the bottom.
Then transplant into prepared hole (Pro Mix HP) in the SIP which as been precharged with a gallon of water from the top, 1g/gallon of MC.
Cheers
The mini-SIPs do work well, but I've found you have to ease the plant into it. For example, I have a new, 10 day old seedling in my 9 oz version (clear solo SIP inside an opaque cover cup).
So far I have only lightly watered it from the top to keep the seedling from drying out, but now, after 10 days, I'm finally seeing roots just showing at the bottom of the cup so I added a small amount of water to the reservoir. That water quickly got absorbed into the surrounding soil but that was it for now.
That little amount of water saturated the bottom inch or two of the soil in the cup but didn't travel much higher than that. But it also gives the roots a chance to see what a wetter section of the pot feels like.
Next day same thing but this time a small amount of water remained in the reservoir so now it goes on my "earn it" program. No more water until the seedling uses up what it's already been given. And I just give it a little at a time, I don't even fill the reservoir even as small as it is.
This process gets the seedling off to a great start and allows the roots to transition to the water roots it'll need at up-pot into a 1L SIP in a week or two.
I find I have to treat a new seedling more like a normal plant and ease the SIP experience in gradually, and by doing it the way I do I have much happier plants much sooner.
And using the clear inner cup allows me to see exactly what's going on; what the roots look like, how wet the soil is, how high the saturated soil level is, whether there's water in the reservoir, etc. Once the plant catches I can be much more liberal with watering, but to start off they get more of a hybrid approach.
Too wet, too early and you get droopy over-watered looking plants like in any other container because that's what they are: over-watered. But even so, they'll grow out of it even if you don't do anything differently. I just like to get them off to a great start as early as possibly so a bit of extra attention in the first couple of weeks can help do just that.